1. Field
Embodiments of the present invention relate to a data I/O controller and a system including the same, and more particularly, to a data I/O controller capable of processing a plurality of external requests at the same time according to a pipeline scheme, and a system including the same.
2. Description of the Related Art
Recently, a solid state drive (SSD), which replaces an existing hard disk drive (HDD) including a magnetic plate as a storage medium, is widely being used. The SSD includes a semiconductor memory device, and especially includes a nonvolatile semiconductor memory device, as a storage medium.
Data processing speed or a data processing unit of the semiconductor memory device included in the SSD may differ from data processing speed or a data processing unit required by an external device of the SSD. Furthermore, there are various limitations in controlling the semiconductor memory device included in the SSD. Accordingly, the performance of the SSD may be deteriorated.
For example, a NAND flash memory that is widely used in a conventional SSD cannot perform an overwrite operation, and instead performs read and write operations by page units while performing an erase operation by block units, wherein a block is larger than a page. And in the NAND flash memory including multi-level cells (MLCs), it takes a longer time to perform the read and write operations than in the NAND flash memory including single-level cells (SLCs). As a result, in the conventional SSD including the NAND flash memory, a bottleneck phenomenon may occur due to such a data processing speed of the NAND flash memory.
In order to solve the above problem, the conventional SSD has employed a write-back method using a volatile memory device. However, even though the write-back method is employed, the SSD still has to access a NAND flash memory. Therefore, an evitable delay may occur during the access to the NAND flash memory. Furthermore, according to the recent trend, a bandwidth required for an operation of the SSD has been increased. Therefore, a bandwidth loss caused by the write-back method may degrade the performance of the SSD.
The above problem has been described in association with the SSD. However, such a problem may occur in any system including a semiconductor memory device as a data storage medium.